[Genetic study of the mutations impairing guanine, xanthine and hypoxanthines assimilation in a purine auxotroph of Escherichia coli K-12].

The hpt gene is responsible for the synthesis of hypoxanthine-guanine phosphoribosiltransferase. This gene was located between aceE and pan markers on the linkage map of Escherichia coli K-12 by a detailed transductional analysis using P1 phage. As described earlier by Nijkamp and De Haan, the guaC mutation blocks the synthesis of guanosine-5'-monophosphate reductase. The cotransduction frequencies of guaC with leu, azi, nadC, aceE, hpt and pan showed the guaC site to be positioned anterior to nadC marker. The order of these genes appeared to be as follows: leu--azi--guaC--nadC--aceE--hpt--pan.